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turbo chef

hi, looking for any good info to read on turbo chef ovens. any help troubleshooting,repairing. haven't had the pleasure of working on one yet, but there are few new restraunt with them coming to town. I'm aware they can be very dangerous, not to test high voltage circuit, etc... are you guys shorting the capacitors like any other capacitor to make sure they are completley discharged, or is there a special procedure with these? What are the more common failures/symptoms? any info is appreciated. thanks

If you have experience working on microwave ovens, all the same safety precautions apply. The high voltage circuit operates at up to 4000 volts, so I always bleed the capacitors first thing once access panels are off. These types of ovens usually have two magnetrons, therefore two high voltage capacitors.

Your best resources for reading are the service manuals. Most are available for download at partstown.com. Turbo Chef's manuals are very well written, with theory of operation and component level testing procedures. These manuals are a necessity for translating fault codes.

Turbo Chef's largest customer is Subway - who pretty much got Turbo Chef's business off the ground. Turbo Chef's competitors are Merry Chef and Amana (XPRESS oven).

These ovens are electronically driven, using solid state relays and an ellaborate programmable control. The door interlocks and monitor switches are about the only mechanical controls. The controller not only stores programming for product modes, it also has test modes to aid in troubleshooting - AND displays fault codes.

The fault codes will generally isolate the problem down to what aspect of operation has failed. Otherwise, typical word-of-mouth problems such as "it takes two hours to preheat" obviously leads to bad heating elements & such.

The biggest problems I've seen with Turbo Chef ovens has been failed magenetrons due to arcing inside the waveguides caused to grease migration. The grease will turn to carbon and causes problems similar to microwaving a metal object - except all the sparking that's doing the damage is isolated from view up inside a waveguide. Next thing ya know - FAULT CODE for low mag current!

Turbo Chef's initial design had the magnetrons and waveguides UNDER the floor of the cooking chamber. THAT was a major contributor to failure since it gave grease an easy route into the wave guides. Those were a nightmare to work on given the failed component location. Turbo Chef smartened up on their later models and moves the mags and wave guides above the roof of the cooking chamber. However, they're still susceptible to failure if the oven isn't properly maintained by the user.

The biggest factor leading to failure is lack of timely & proper cleaning - AGAIN, ultimately leading to grease migration and magnetron failure.

When you have found a unit with a failed magnetron, don't just order a new mag. Remove and inspect the wave guides. You'll usually find you will need to replace those as well. I also recommend replacing the high voltage capacitor and diode whenever replacing a magnetron.

Final recommendation: Program the tech support numbers for all three manufacturers into your phone. For Amana's number, Google "Comserv".

thanks for taking the time for a great response. When you discharge these caps, how exactly are you doing to make sure everything is safe? shorting across post to post for a few seconds with screwdriver or something else? I have not worked on alot of microwaves yet, but will download and read there manuals for sure. thanks

You got it. Something with a well insulated handle. A screwdriver usually. If you visibly made good metal contact across the capacitor terminals for a second - and nothing happens, then it's already discharged.

On a rare occasion that youcome across a charged capacitor, you'll hear. It's instantaneous. Nothing overly alarming like say...a gun going off. Just a little "snap" about as loud as flicking a cigarette lighter.

Of course, I've always wondered in anticipation whether the next one might be one packing more of a whallop.

Truthfully, they're usually already discharged. But occasionally a failed magnetron will cause a capacitor to remained charged.

Microwave are really quite simple when you divide the circuitry up and learn to understand what does what and what generally fails.

Low voltage side is all control and input to the power transfomer primary winding. There's only a handful of components comprising the high voltage secondary circuit. You can only do voltage tests up to the primary winding. You can only test high voltage components with an ohmeter or capacitance tester.

I don't have much to add to EC's postings; he has hit it all pretty much on the head.

Turbochef does have tech support as well, but my experience with them has been lukewarm. They WILL help you through a problem, but they prefer you go through the manual first. Also, they offer training in their Dallas facility - you would have to call and register for a class.

I have found when the mags short from the grease build up, it takes out the cap on the mag end - which winds up rolling around somewhere in the wave guide. Then you gotta pull the wave guide. Then you may as well change the wave guide covers since you have it all out. A real PITA.

I work for subway, at 16 locations, most with two ovens. Most are turbochefs, but some merrychefs,, like the merrychefs better and they seem to break less.
Turbo chefs will show you the fault codes.
Parts I keep on hand,
Magnetrons
Diodes
Caps
High voltage transformers
Microswitches
Cooling fan
Almost forgot guidecovers,,

Also, merrychef classes are availabe at the same location in Dallas, and I recommend them, you get a good indepth class, lit and parts lists, good stuff.